This application claims the benefit of International Application No. PCT/EP97/05256, which claims priority from European Application No. EP96202789.2 filed Oct. 8, 1996.
The present invention relates to a packaging wrapper consisting of a film intended to be closed by two twists on either side of an article to be packaged, and to a process for packaging an article with the aid of such a package. In particular, the invention relates to the field of the packaging of confectionery products.
Confectionery are generally packaged individually in a preprinted piece of film of an appropriate size and shape, it being possible for the said individually packaged products to be, in their turn, packed in bulk in a small packaging bag of an appropriate size. The article to be packaged is typically first of all completely wrapped in a rectangular piece of film and the package thus formed is closed by twists at two points situated on either side of the article to be packaged.
In the context of the present invention a twist is intended to mean the result of the closure by twining of the said wrapper.
An important problem which presents itself in this respect is that of the retention of the twist. This retention can be obtained only at the cost of a particular selection of the film employed as substrate, which must exhibit appropriate mechanical characteristics such as pliability or, in particular, a pronounced tendency not to return to its initial position after the twining of the said film.
In particular, this problem becomes apparent when articles of small sizes and of essentially round section are being packaged, such as confectionery products like, for example, bonbons, lollipops, barley sugar, fruit jellies, chocolate-coated bars or else more bulky products such as bottles, rolls of articles, etc.
As solution, it is known to select particular substrates which are known for their high pliability, like waxed paper or cellophane or synthetic films containing an appropriate quantity of an additive increasing the pliability of the said substrate.
This solution considerably restricts the potential choices of films employed as packaging substrate and considerably increases their cost.
Packages closed by twists, which are produced from substrates precoated with a heat-sealing coating, are known on the market. When twists are being formed at the ends of the wrapper containing the article to be packaged, a source of heat at a temperature of approximately between 120 and 160xc2x0 C. is approached for a certain period of time. In general, it is the jaws performing the twining that are heated, but it is also possible to blow hot air by means of a pipe of appropriate size onto the said twists, and this results in the melting of the heat-sealing coating and the sealing of the twist thus formed when the said heat-sealing coating is cooled.
Document GB-A-1096058 proposes a film with a cold-sealing coating which exhibits an excellent retention after closure of the wrapper by twining of the twists. This cold-sealing coating is in the form of two lengthwise strips situated in the regions of formation of the twists on either side of the article to be packaged.
Cold-sealing is intended to mean sealing which takes place instantaneously merely by contact at a temperature of approximately between 0 and 50xc2x0 C. In reality, the temperature is not a critical parameter for obtaining sealing by means of a cold-sealing coating and has practically no effect on the quality of the sealing obtained. The sealing is therefore performed without an additional heat input being necessary at the ambient temperature of the space in which the packaging unit is situated.
This method therefore makes it possible to employ films which are less expensive and have better properties (rigidity, printability, aesthetic qualities) for the packaging of articles without any restrictions as to the shape or the heat-sensitivity of the said articles.
The objective of the present invention is to provide a novel packaging of the type with closure by twists, which allows a better closure than the currently known packages, as well as a novel packaging process.
To attain this objective the present invention provides a packaging wrapper consisting of a film intended to be closed by two twists on either side of an article to be packaged, characterized in that the film comprises, on the internal side in relation to the article to be packaged, a sealing coating placed along two transverse strips on either side of the article to be packaged and extending parallel to an axis passing through the two twists.
The said sealing coating may be a cold-sealing coating or a heat-sealing coating.
The film may additionally comprise two lengthwise strips of sealing coating extending on either side of the strips of sealing coating extending on either side of the article to be packaged, perpendicularly to the said transverse strips in the regions of formation of the twists. These sealing coatings may also be either cold-sealing coatings or heat-sealing coatings. When the substrate of the film has a low resistance to elevated temperatures and/or when the article to be packaged is heat-sensitive, especially products of chocolate manufacture, the cold-sealing coating deserves to be preferred.
The heat-sealing coating may be a layer of PE (polyethylene) coextruded onto OPP (oriented polypropylene).
As cold-sealing coating, it is possible to envisage pressure-sensitive adhesives, which are substances which are continually adhesive and which adhere spontaneously to the surface of most materials under the effect of a simple moderate pressure.
As a general rule the pressure-sensitive adhesives are compositions based on natural and/or synthetic rubber, used in combination with modified cellophanes, phenol-formaldehyde resins or hydrocarbon resins (waxes). Besides rubbers, polymers based on styrene, (meth)acrylic acid or vinyl ether are widely employed, alone or as a mixture, also in combination with resins. Lastly, silicone resins may also be employed. Compositions including mixtures of natural and synthetic rubbers and copolymers of (meth)acrylic acid and styrene are preferably employed.
These cold-sealing coatings are deposited onto the substrate at a rate of approximately from 1 to 5 g/m2. They can be applied in the form of solution or dispersion or even in the molten state. Coating deposition techniques which are well known to a person skilled in the art may be employed, such as, for example, heliographic or flexographic printing or else offset printing.
The invention also proposes a process for packaging an article in a film comprising at least two transverse strips of a sealing coating, according to which the article is deposited on the film on the side of the said strips and between the latter, the two sections which are provided with the said strips of coating are raised substantially vertically, the two sections are brought close on top of the article and their edges are sealed to one another, the two edges thus sealed are folded back over the article and the projections of the film extending beyond on either side of the article are twined to form two twists.
When the strips of coating comprise a cold-sealing coating, the operation of folding and sealing the edges of the strips on top of the article is preferably carried out as a single operation between the jaws of a press.
When the coating is a heat-sealing coating, the edges are sealed to each other by a heat-sealing process.
The invention has the advantage that, for the first time, the package of the twist-closure type is sealed in the transverse direction between the two twists. Given that even the packages without lengthwise coating in the regions of formation of the twists have a leakproofing which is rather good at the twists, packages which are completely closed are thus produced.
With regard to the packages provided with lengthwise regions of heat- or cold-coating, in the case of which there is a leakproof closure at the twists, a virtually hermetic closure is produced by virtue of the transverse sealing. This complete closure of the package is very advantageous with regard to the conservation of the articles, since it prevents the entry of moisture, of gas, of air or of other harmful substances and, at the same time, preserves the flavours within the packaging.
The invention will be understood better on reading the description of a few embodiments which are presented below, by way of illustration, with reference to the attached drawings.